Gear transmission having variable shaft distance



April 13, 1954 E. H. MUDERSBACH 2,674,898

GEAR TRANSMISSION HAVING VARIABLE SHAFT DISTANCE Filed Dec. 4. 1950 c x [I o In; a t I s 'IIIIIIIlIIIIlI/I/IIIII 7 /////////I/IIIIIIIIIIIIII Ad 4026 (SP/V1719! M6 06 13196 )7 46:. ,afrazwzr Patented Apr. 13. 1954 GEAR TRANSMISSION HAVING VARIABLE SHAFT DISTANCE Ernst ll. Mudersbach, Heidelberg, Germany, as-

signor, by mcsne nssi Marble, New York, N. Y.. Leslie M. Merrill, Westfield, N. J., and Percy H. Batten, Racine.

Wis., trustees gnments, to Jarvis C.

Application December 4, 1950, Serial No. 198.971

9 Claims.

The present invention relates to gear transmissions and has particular reference to such transmissions embodying gears of large diameter.

Large gears are often subject to distortion due to strains set up upon assembly and also due to diii'erential expansion resulting from uneven heating, as in peripheral gear drives for the rotors of regenerative heat exchangers. Such distortion may. in the case of very large gears.

result in teeth being brought out of mesh and/or being meshed so deeply as to overstress and damage the gear or its supporting bearings.

It is the general object of the present invention to provide a novel and improved form of gear transmission, particularly for large gears. which will eliminate deficiencies of the kind noted above, and to this end the invention contemplates the provision of gears having intermeshing teeth and circular rim portions rigidly concentric with the pitch circles of the gears and with the rim portions confronting in a common plane and having diameters so related that they engage only when the depth of mesh between the teeth tends to exceed the maximum permissible value. Further, the invention contemplates the mounting of one of the gears on a movable shaft which is subjected to a biasing means, such as a spring or a weight, tending to move th gear on the movable shaft into mesh with its cooperating gear. With such an arrangement, overmeshing of the teeth is prevented by the rims and undermeshing is prevented by the biasing means. even in cases where distortion of substantial magnitude tends to occur.

In some instances it is desirable to provide an adjustable stop for limiting the inward or meshing movement of the movably mounted gear, so that small variations from true circular shape of one or both of the gears may be taken up by variation in the mesh of the teeth and only larger distortions taken up by contact of th rim portions. Small variations can readily be taken up by variations in the meshing of the teeth without difficulty if the teeth are of involute form and the invention further contemplates the use if desired of that form of tooth. Also, it is frequently desirable for the purpose of effecting peripheral drive of large regenerative heat exchange rotors. to make the rotor gear in the form of a rack comprised of a number of pins with which the teeth of a pinion gear mesh. Such forms of a drive are known per se but the usual form of round pin or bolt does not permit satisfactory variation of the depth of mesh, and the invention further contemplates in the construction of such type of gearing the shaping of the meshing surfaces of the pins or bolts to involute form to permit changes in the depth of mesh within prescribed limits.

Fig. l is a fragmentary sectional view of the rim portions of two intermeshing gear wheels embodying the invention.

Fig. la is a side elevation of the gear wheels shown in Fig. 1.

Fig. 2 shows an embodiment of the invention as applied to a rotary regenerative heat exchanger.

Fig. 3 shows a rack having round bolts the surfaces of which are machined to involute form.

Fig. 3b is a side elevation of the gear wheels shown in Fig. 3.

Referring now to the embodiment of the invention shown in Figs. 1 and la, the gear wheels Ill and I2 are shown as being provided with intermeshing teeth It and I8 respectively which may advantageously be of involute form as shown.

Adjacent to these teeth and rigidly concentric with the pitch circles of the gears are the rim portions a and b which, as will be seen from Fig. 1, confront each other in a common plane. As will also be seen from the figures, the diameters of these rim portions are such that when the teeth are in normal mesh, the rims are not in contact, coming into contact only when distortion of one or both of the gears tends to cause the depth of mesh of the teeth to exceed the permissible maximum amount.

In Fig. 2 the invention is shown applied to the rotor IB of a regenerative heat exchanger, rotatably carried by hearing 20 and at its rim being provided with a gear in the form of a rack comprised of a number of bolts or pins 22. The driving pinion or gear 24 in this embodiment is rotatably carried by a bearing 26 in a frame 28 pivotally mounted at 36. The pinion 24 is biased into mesh with the rack by means of spring 32 and the depth of normal mesh is established by the adjustable sto 34.

In Fig. 3 there is shown in section a gearing embodying pins 22 of the kind shown in Fig. 2, these pins being provided with involute meshing surfaces 38, as seen more clearly in Fig. 3b.

While suitable examples of gearing embodying the invention have been shown and described by way of example, it will be understood that the invention contemplates all forms of apparatus falling within the scope of the appended claims.

I claim:

1. Gearing comprising a pair of shafts, a pair of gears fixed radiall with respect to the axes of said shafts, said gears having intermeshing teeth and circular rim portions laterally adjacent. to the teeth and rigidly concentric with the p tch circles of the gears, said rim portions having a common plane and having diameters so related to the diameters of the pitch circles of the teeth of the gears that said rim portions are out of contact with each other when the teeth are properly meshed and. are operative to engage to limit the depth of engagement of the meshing teeth in the event of distortion or expansion of the gears.

2. Gearing as defined in claim 1 in which the diameters of said circular rims are smaller than but approximately the same as that oi the respective pitch circles of the gears.

3. Gearing as defined in claim 1 in which one. oi said shafts is mounted to have movement toward or away from th other of the shafts and in which the gearing includes means for biasing the movable shaft toward the other shaft.

4. Gearing as defined in claim 3 in which ad- Justable stop means is provided to positively limit the minimum distance between said shafts.

5. Gearing as defined in claim 4 in which one of said gears is provided with teeth formed by a series of pins or bolts shaped with involute faces.

6. Apparatus oi the character described comprising a. rotor for a regenerative heat exchanger having a rotor gear thereon subject to heat distortion as the rotor is revolved, and a driving pinion gear meshing with said rotor gear to turn the rotor, said gears having coplana circular rims concentric with the pitch circles or the gears and having diameters so related to the pitch cles of the teeth of the gears that said rims are out of contact with each other when the teeth are properly meshed and are operative to engage to limit the depth Of engagement of the meshing teeth in the event of expansion of said rotor gear due to heat distortion thereoi.

'1. Apparatus as defined in claim 6 in which said pinion gear is pivotally mounted and yieldably biased in engagement with said rotor gear.

8. Apparatus as defined in claim 6 in which said rotor gear is many times the diameter or said pinion gear and is formed by a multiplicity 01' separate pins separately mounted in the rotor structure.

9. Apparatus as defined in claim 8 in which said pins are formed with involute faces for meshing engagement with the teeth or said pinion 869-1.

References Cited in the tile of this patent UNITED STATES PATENTS Number Name Date 106,360 Hamlin Aug. 16, 1870 244,938 Sheridan July 26, 1881 1,169,458 Buliard et a1 Jan. 23, 1916 1,377,176 Anderson May 10, 1921 ,832,137 Peters Nov. 17, 1931 2,441,901 Petersen May 18, 948

2,605,646 Karlssen et a1. Aug. 5, 1952 

